Fewer basements, more crawlspaces
Full basements are less common in the Sacramento area than in colder regions, and many homes sit on slabs or raised foundations with crawlspaces. Whether you have a basement, a partial basement, a cellar or a crawlspace, the challenge is the same: keeping water and moisture out of the space below the house.
Groundwater and river flood risk
Sacramento sits where the American and Sacramento rivers meet, and much of the city depends on levees. The Sacramento River East Levee alone protects essentially all of the city south of the American River and west of Highway 99. In wet years, groundwater can rise close to the surface in low-lying areas, and basements and crawlspaces can take on water even without a flood. Sump pumps are common in homes with basements and in some crawlspaces. If yours has one, test it before the rainy season by filling the pit until the pump runs, make sure the discharge carries water well away from the foundation, and consider a battery backup, since storms can bring outages.
Winter rain and fog
Most of Sacramento's rain falls in winter, and tule fog can keep the ground and air damp for days. Crawlspaces with exposed soil, blocked vents or poor drainage stay wet through the season, which can lead to mold on floor framing, wood decay and musty air in the house. A heavy vapor barrier over crawlspace soil, clear vents or a properly conditioned space depending on the design, and good drainage are the foundations of a dry crawlspace.
Outside first
Many below-grade water problems in Sacramento start with the basics: clogged gutters, short downspouts, flat or reverse-sloped soil against the house, and sprinklers spraying the foundation. Fixing those is inexpensive and often solves the problem.
Finishing a basement
If you have a basement and want to finish it, confirm it stays dry through a full rainy season first, test for radon, and plan for egress windows in any bedroom. Use moisture-tolerant materials, and include a dehumidifier.
Flooding
If floodwater reaches your basement or crawlspace, wait until officials say it's safe, have the electrical system checked, and remove wet insulation and porous materials. Dry the space thoroughly before rebuilding.
Before you hire
Ask Sacramento contractors where the water is coming from, whether outside fixes could solve it, what sump pump and backup they recommend, how they'll handle crawlspace moisture, and whether permits are needed. Look up the contractor's California license with the CSLB.
Termites and crawlspaces
Termites are present in the Central Valley. Damp crawlspaces with wood touching soil invite them. Keep the crawlspace dry, remove wood debris, and make sure posts sit on concrete piers.
Radon
The EPA recommends testing all homes for radon. A simple test kit tells you whether a basement or crawlspace needs mitigation.
Sealed pit lids
A sealed lid on the sump pit keeps humid air and soil gases out of the space, and keeps debris and children out of the pit.